Merge pull request #15983 from kpayson64/write_stalling_fix

Write stalling fix

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -813,7 +813,11 @@ static void set_write_state(grpc_chttp2_transport* t,
                                  write_state_name(st), reason));
   t->write_state = st;
   if (st == GRPC_CHTTP2_WRITE_STATE_IDLE) {
-    GRPC_CLOSURE_LIST_SCHED(&t->run_after_write);
+    grpc_chttp2_stream* s;
+    while (grpc_chttp2_list_pop_waiting_for_write_stream(t, &s)) {
+      GRPC_CLOSURE_LIST_SCHED(&s->run_after_write);
+      GRPC_CHTTP2_STREAM_UNREF(s, "chttp2:write_closure_sched");
+    }
     if (t->close_transport_on_writes_finished != nullptr) {
       grpc_error* err = t->close_transport_on_writes_finished;
       t->close_transport_on_writes_finished = nullptr;
@@ -1208,7 +1212,10 @@ void grpc_chttp2_complete_closure_step(grpc_chttp2_transport* t,
         !(closure->next_data.scratch & CLOSURE_BARRIER_MAY_COVER_WRITE)) {
       GRPC_CLOSURE_RUN(closure, closure->error_data.error);
     } else {
-      grpc_closure_list_append(&t->run_after_write, closure,
+      if (grpc_chttp2_list_add_waiting_for_write_stream(t, s)) {
+        GRPC_CHTTP2_STREAM_REF(s, "chttp2:pending_write_closure");
+      }
+      grpc_closure_list_append(&s->run_after_write, closure,
                                closure->error_data.error);
     }
   }
@@ -2009,6 +2016,10 @@ static void remove_stream(grpc_chttp2_transport* t, uint32_t id,
 
 void grpc_chttp2_cancel_stream(grpc_chttp2_transport* t, grpc_chttp2_stream* s,
                                grpc_error* due_to_error) {
+  GRPC_CLOSURE_LIST_SCHED(&s->run_after_write);
+  if (grpc_chttp2_list_remove_waiting_for_write_stream(t, s)) {
+    GRPC_CHTTP2_STREAM_UNREF(s, "chttp2:pending_write_closure");
+  }
   if (!t->is_client && !s->sent_trailing_metadata &&
       grpc_error_has_clear_grpc_status(due_to_error)) {
     close_from_api(t, s, due_to_error);

src/core/ext/transport/chttp2/transport/internal.h

@@ -54,6 +54,8 @@ typedef enum {
   /** streams that are waiting to start because there are too many concurrent
       streams on the connection */
   GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY,
+  /** streams with closures waiting to be run on a write **/
+  GRPC_CHTTP2_LIST_WAITING_FOR_WRITE,
   STREAM_LIST_COUNT /* must be last */
 } grpc_chttp2_stream_list_id;
 
@@ -431,9 +433,6 @@ struct grpc_chttp2_transport {
    */
   grpc_error* close_transport_on_writes_finished;
 
-  /* a list of closures to run after writes are finished */
-  grpc_closure_list run_after_write;
-
   /* buffer pool state */
   /** have we scheduled a benign cleanup? */
   bool benign_reclaimer_registered;
@@ -584,6 +583,7 @@ struct grpc_chttp2_stream {
 
   grpc_slice_buffer flow_controlled_buffer;
 
+  grpc_closure_list run_after_write;
   grpc_chttp2_write_cb* on_flow_controlled_cbs;
   grpc_chttp2_write_cb* on_write_finished_cbs;
   grpc_chttp2_write_cb* finish_after_write;
@@ -686,6 +686,13 @@ bool grpc_chttp2_list_pop_stalled_by_stream(grpc_chttp2_transport* t,
 bool grpc_chttp2_list_remove_stalled_by_stream(grpc_chttp2_transport* t,
                                                grpc_chttp2_stream* s);
 
+bool grpc_chttp2_list_add_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                   grpc_chttp2_stream* s);
+bool grpc_chttp2_list_pop_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                   grpc_chttp2_stream** s);
+bool grpc_chttp2_list_remove_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                      grpc_chttp2_stream* s);
+
 /********* Flow Control ***************/
 
 // Takes in a flow control action and performs all the needed operations.

src/core/ext/transport/chttp2/transport/stream_lists.cc

@@ -35,6 +35,8 @@ static const char* stream_list_id_string(grpc_chttp2_stream_list_id id) {
       return "stalled_by_stream";
     case GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY:
       return "waiting_for_concurrency";
+    case GRPC_CHTTP2_LIST_WAITING_FOR_WRITE:
+      return "waiting_for_write";
     case STREAM_LIST_COUNT:
       GPR_UNREACHABLE_CODE(return "unknown");
   }
@@ -214,3 +216,18 @@ bool grpc_chttp2_list_remove_stalled_by_stream(grpc_chttp2_transport* t,
                                                grpc_chttp2_stream* s) {
   return stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
 }
+
+bool grpc_chttp2_list_add_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                   grpc_chttp2_stream* s) {
+  return stream_list_add(t, s, GRPC_CHTTP2_LIST_WAITING_FOR_WRITE);
+}
+
+bool grpc_chttp2_list_pop_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                   grpc_chttp2_stream** s) {
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_WAITING_FOR_WRITE);
+}
+
+bool grpc_chttp2_list_remove_waiting_for_write_stream(grpc_chttp2_transport* t,
+                                                      grpc_chttp2_stream* s) {
+  return stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_WAITING_FOR_WRITE);
+}